Optical unit for use in a light-sensitive sorting machine

ABSTRACT

An optical unit for use in a light-sensitive sorting machine comprising a chamber having a plurality of adjacent vertically extending channels therethrough through which may fall matter to be sorted, a plurality of fluorescent light-producing means for directing visible light onto matter falling through the channels, at least one of the fluorescent light-producing means being arranged to direct the visible light into a plurality of the said channels, and optical viewing means which view the matter falling through each channel.

Jan. 9, 1973 United States Patent 1 Chapman m T S m. .l n 8 L m Am w. mC m E d M yn U fa G fle R mn 0.1 E FT R M T I 0 mm m 3 E MW Td mm m m m 0% m M M. h. H.

[73] Assignee: Gunsons Sortex Llmlted, London,

England Primary Examiner-Joseph F. Peters, Jr. Attorney-Cushman, Darby 8L Cushman [22] Filed: Jan. 4, 1971 [57] ABSTRACT An optical unit for use in a light-sensitive sorting [30] Foreign Application Priority Data machine comprising a chamber having a plurality of .lan.5,1970 adjacent vertically extending channels therethrough Great Britain..........................398/70 through which may fall matter to be sorted, a plurality of fluorescent light-producing means for directing visi- [52] [1.8. C|...........240/51.11 R, 209/11l.7, 250/223 [51] Int. Cl.......B07c 5/342, G06m 7/00, HOlj 39/12 ble light onto matter falling through the channels, at [58] Field of Search.240/47, 51.11, 11.2, 218, 111.5; least one of the fluorescent light-producing means 209/1 1 L 11 1 being arranged to direct the visible light into a plurali- 104 ty of the said channels, and optical viewing means which view the matter falling through each channel.

[5 6] References Cited UNITED STATES PATENTS 10 Claims, 4 Drawing Figures 3,066,797 12/1962 Fraenkel.......................250/223RX PAIENTEDJAI 9 i973 SHEET 1- BF 2 H QM Qm V v kin}.WFPIRVIII IiPElRMMQNIRIMMIMW who NY R OPTICAL UNIT FOR USE IN A LIGHT-SENSITIVE SORTING MACHINE This invention concerns an optical unit for use in a light sensitive sorting machine.

According to the present invention there is provided an optical unit for use in a light-sensitive sorting machine comprising a chamber having a plurality of adjacent vertically extending channels therethrough through which may fall matter to-be sorted, a plurality of fluorescent light-producing means for directing visible light onto matter falling through the channels, at least one of the fluorescent light-producing means being arranged to direct the visible light into a plurality of the said channels, and optical viewing means which view the matter falling through each channel.

As will be appreciated, since the optical unit of the present invention employs fluorescent light-producing means, as opposed to the tungsten light sources which are conventionally used in light-sensitive sorting machines, the light directed towards the matter being sorted is of a diffuse nature and there is therefore no need to provide lamp guards for preventing direct illumination of this matter.

Moreover, not merely may the fluorescent lightproducing means readily be arranged to have a life expectancy very much larger than that of conventional tungsten light sources, e.g. a life expectancy of up to 5,000 hours, but also these fluorescent light producing means may be arranged to have a high light-producing efficiency and thus to run cool, so extending the life of the fluorescent light-producing means in tropical enviroments.

Furthermore, by reason of the fact that, in contrast to the conventional tungsten light sources, such fluorescent light-producing means run cool, the danger that any dust within the unit will become baked upon the fluorescent lightproducing means, or on light reflecting surfaces of the unit, is reduced.

The said at least one fluorescent light producing means may be disposed between two adjacent channels.

The fluorescent light-producing means may comprise vertically extending fluorescent tubes. Such an arrangement provides a large degree of top and bottom lighting for the matter falling through the channels.

' Preferably, at each of opposite sides of each channel,

there is provided a replaceable light-producing component which may be readily inserted into and withdrawn from the optical unit, each said lightproducing component comprising a sealed, at least partially translucent, container which contains fluorescent tubes the light from which may pass through translucent portions of the container. As will be appreciated such an arrangement provides ease of servicing.

The said container may, for example, be fabricated wholly from a translucent synthetic resin material.

Each said channel may be substantially rectangular in cross section, the sides of the channel which are not provided with the said fluorescent light-producing means being respectively provided with the opticalviewing means and with a background holder member, the background holder member being adapted to hold a background against which the matter falling through the channel may be viewed by the optical viewing means. Thus the position of each background holder member may be adjusted so as to adjust the effective reflectivity thereof.

Preferably, common air supply means are provided for supplying flows of dust-removing air past the optical viewing means of all the channels. Moreover, the said common air supply means may also supply flows of dust-removing air past the background holder members of all the channels. The said flows of air preferably pass from the top to the bottom of each. channel.

The optical unit is preferably readily insertable into and withdrawable from the said sorting machine.

The invention also comprises a light-sensitive sorting machine provided with an optical unit as set forth above, the optical unit being a friction fit in the machine.

The invention is illustrated, merely by way of example, in the accompanying drawings, in which:

FIG. 1 is a plan view of an optical unit according to the present invention for use in a light-sensitive sorting machine,

FIG. 2 is an end view of the optical unit shown in FIG. 1,

FIG. 3 is a side view of the optical unit shown in FIG. I, and

FIG. 4 is a sectional view taken on the line 44 of FIG. 3.

In the drawings there is shown an optical unit 10 which may readily be inserted into and withdrawn from a light-sensitive sorting machine (not shown) by reason of being a friction fit in the latter.

The optical unit 10 comprises a chamber 1 1 having a plurality, e.g. six as shown, of adjacent vertically extending channels 12 to 17 therethrough which are open at their top and bottom and through which may fall matter to be sorted, e.g. agricultural produce or mineral matter.

Each of the channels 12 to 17 is substantially rectangular in cross section having sides 20 to 23. At each of the opposite sides 20, 22, of each channel 12 to 17 there is provided a replaceable light-producing component 24 which may readily be inserted into and withdrawn from a holder 25 in the optical unit 10. Each of the light-producing components 24 comprises a sealed container 26 which is fabricated wholly from a translucent synthetic resin material which may or may not be transparent, such for example, as methyl methacrylate, the translucent container 26 containing three vertically extending visible light producing, fluorescent tubes 27 each of which extends substantially from the top to the bottom of its respective channel. Thus the light from the fluorescent tubes 27 may pass through the translucent wall of the container 26 so as to be directed onto any matter to be sorted which falls through the respective channel. It will, moreover, be noted that with the exception of the light-producing components 24 at the ends of the unit 10, each of the remaining light-producing components 24 is disposed between an adjacent pair of channels so as to direct light into both of the channels of the said pair.

Those sides 21, 23 of each channel which are not provided with the light-producing components 24, are respectively provided with a lens tube 30, for viewing the matter falling through the channel, and with a background holder 31. The latter is provided for holding a background (not shown) against which the matter falling through the respective channel may. be viewed by the respective lens tube 30 The position of each of the background holder members 31 may be adjusted (not shown) towards and away from the center of the respective channel so as to adjust the effective reflectivity thereof. The background held by the background holder member 31 is selected to have a color corresponding to that which it is desired should be possessed by the matter falling through the channel.

The lens tube 30, which is protected from dust by means of a translucent cover plate 32, thus receives light which has been directed onto the matter being sorted by the fluorescent tubes 27 and which has been either reflected by the said matter or transmitted therethrough. The light passing through each lens tube 30 is directed thereby onto a respective photoelectric amplifier 33 which is adapted to produce electrical signals representative of the light reflected by or transmitted through the said matter. These signals are employed to effect operation of an ejector 34 which is provided beneath each of the channels 12 to 17 and which is arranged to be periodically operated so as to separate undesired from desired matter.

Thus the said matter may be fed (by means not shown) through the open top of each of the channels 12 to 17, may be viewed while passing through each of these channels, and then pass adjacent to the ejectors 34 so as to be capable of being deflected thereby if necessary. The ejectors 34 may, for example, be pneumatically operated.

The matter passing through the channels 12 to 17 entrains a certain amount of dust, while the operation of the ejectors 34 will tend to cause this dust to be thrown up into the optical unit 10. It is important to ensure that this dust does not settle on certain parts of the unit if the operation of the optical unit 10 is not to be adversely affected.

For this reason the optical unit 10 is provided with twoair inlets 35, 36 to which a supply of cool, dustremoving, air is provided. Air supplied to these air inlets 35, 36 may pass through spaces within the optical unit 10 so as to reach slots 40, 41, which are adjacent to the respective photoelectric amplifiers 33, and slots 42, 43, which are adjacent to the respective background holder members 31. The slots 40 to 43 are disposed adjacent to the top of the optical unit 10 so that the flows of dust-removing air pass from the open top to the open bottom of each of the channels 12 to 17. As indicated by the arrows 44 in FIG. 4, flows of dust-removing air are supplied past the lens tube 30, there also being flows (not shown) of dust-removing air past the background holder members 31 so as to prevent dust from settling on these parts.

The arrangement is thus such that the optical unit 10 itself "is provided with common air supply means for supplying the flows of dust-removing air past the lens tubes and background holder members, the bulky and unhygienic hoses which would otherwise be required for supplying such flows being dispensed with.

If the optical unit .is used in a sorting machine sorting foodstuffs, it is desirable that the containers 26 are not made of glass and for this reason it is preferred, as indicated above, to make them of a material such as methyl methacrylate, e.g. that sold under the Registered Trade Mark Perspex". Such material, however, tends to become electrically charged more easily than glass itself, and thus to attract dust. It will be a preciated that the said flows of air also serve to pass over the containers 26 so as to reduce the risk of dust settling on these containers. Moreover, since these flows of air will serve a cooling purpose, this will have directing the visible light into a plurality of the said channels, and optical viewing means which are disposed .adjacent to and which view the matter falling through each channel. I

2. An optical unit as claimed in claim 1 in which the said at least one fluorescent light producing means is disposed between two adjacent channels.

3. An optical unit as claimed in claim 1 in whichthe fluorescent light-producing means comprise vertically extending fluorescent tubes.

4. An optical unit as claimed in claim 1, in which, at each of the opposite sides of each channel, there is provided a sealed, at least partially translucent container which may be readily inserted into and withdrawn from the optical unit, each said container containing fluorescent tubes the light from which may pass through translucent portions of the container.

5. An optical unit as claimed in claim 4 in which the said container is fabricated wholly from a translucent synthetic resin material.

6. An optical unit as claimed in claim 1 in which each said channel is substantially rectangular in cross section, the sides of the channel whichare not provided with the saidfluorescent light-producing means being respectively providedv with the optical-viewing means and with a background holder member, the background holder member being adapted to hold a background against which the matter falling through the channel may be viewed by the optical viewing means. j

7. A optical unit as claimed in claim 6 in the position of each background holder member may be adjusted so as to adjust the efiective reflectivity thereof.

8. An optical unit as claimed in claim 6 in which common air supply means are provided for supplying flows of dust-removing air past the optical viewing means of all the channels.

9. An optical unit as claimed in claim 8 in which the said common air supply means also flows of dustremoving air past the background holder members of all the channels.

10. An optical unit as claimed in claim 8 in which the said flows of air pass from the top to the bottom of each channel. 1 

1. An optical unit for use in a light-sensitive sorting machine comprising a chamber having a plurality of adjacent vertically extending channels therethrough, through which may fall matter to be sorted, a plurality of fluorescent light-producing means which direct visible light onto matter falling through the channels, at least one of the fluorescent light producing means directing the visible light into a plurality of the said chanNels, and optical viewing means which are disposed adjacent to and which view the matter falling through each channel.
 2. An optical unit as claimed in claim 1 in which the said at least one fluorescent light producing means is disposed between two adjacent channels.
 3. An optical unit as claimed in claim 1 in which the fluorescent light-producing means comprise vertically extending fluorescent tubes.
 4. An optical unit as claimed in claim 1, in which, at each of the opposite sides of each channel, there is provided a sealed, at least partially translucent container which may be readily inserted into and withdrawn from the optical unit, each said container containing fluorescent tubes the light from which may pass through translucent portions of the container.
 5. An optical unit as claimed in claim 4 in which the said container is fabricated wholly from a translucent synthetic resin material.
 6. An optical unit as claimed in claim 1 in which each said channel is substantially rectangular in cross section, the sides of the channel which are not provided with the said fluorescent light-producing means being respectively provided with the optical-viewing means and with a background holder member, the background holder member being adapted to hold a background against which the matter falling through the channel may be viewed by the optical viewing means.
 7. A optical unit as claimed in claim 6 in the position of each background holder member may be adjusted so as to adjust the effective reflectivity thereof.
 8. An optical unit as claimed in claim 6 in which common air supply means are provided for supplying flows of dust-removing air past the optical viewing means of all the channels.
 9. An optical unit as claimed in claim 8 in which the said common air supply means also flows of dust-removing air past the background holder members of all the channels.
 10. An optical unit as claimed in claim 8 in which the said flows of air pass from the top to the bottom of each channel. 